FIELD OF THE INVENTION
The present invention relates to a cell for fractionating and observing a liquid in a device for analysing this liquid comprising a rotor, a central distribution container for said liquid, and an assembly of such fractionating cells on the periphery of the rotor, each connected to the cup by a liquid feed and gas evacuating duct parallel to the feed duct.
French Patent No. 81019496 filed on May 13, 1981 in the name of the Societe Nationale Elf Aquitaine concerns such a cell. In fact, the cell according to this French patent which discloses a liquid analysis device, is intended to collect a liquid sample fraction to be analyzed in identical cells arranged on the periphery of the rotor. The rotation of this rotor, and the effect of the centrifugal force resulting therefrom, is used to effect the distribution of the liquid fraction delivered to the various identical analysis cells, from a central distribution cup or container.
Each sampled fraction is contacted with a reactive agent comprising an indicator, and is then examined through the cell walls, by means of a suitable device.
The various embodiments described in this French Patent No. 8109496 relate to preventing the formation of air and gas bubbles in the cell; or more precisely, to facilitating the evacuation of such bubbles during the centrifugation by permitting a complete filling of the said cell.
Furthermore, the embodiments described in this French Patent No. 8109496 concern, more especially, ducts for the liquid feed and gas evacuation of the cell, these ducts being able, possibly, to coincide along a part of their length. In particular, it is foreseen to realize cells and ducts through molding plastic pieces welded to one another, with ribs being provided on the internal face of one and/or other of these sheets permitting the said ducts. It is, of course, advantageous to reduce, as much as practically possible, the volume of the ducts that constitutes harmful empty spaces.
The ojects of the present invention is to provide a cell and ducts from molded plastic pieces, and presenting extremely reduced empty spaces, this cell allowing, furthermore, an evacuation as complete as possible of the gases as well as a filling as complete as possible of the cell system, by the liquid to be analyzed.
The fraction collecting and analysing cell device according to the invention comprises a rotor, a central distribution cup of the said liquid, an assembly of such fraction and analysing cells on the periphery of the rotor, each connected to the cup by a liquid feed and gas evacuation cup coinciding in a single channel, cell and duct being formed through molding of plastic pieces, in a manner known per se, and the liquid feed and gas evacuation duct being formed by the space existing between the two plastic pieces welded to each another by two welding seams along the edge of the said duct the opposite faces of the said pieces that constitute the duct with the said welding lines being left in the rough state from molding.
In a surprising way, the irregularities and asperities of the rough molding faces of the two faces forming the liquid feed and gas evacuation duct, are sufficient to allow between these pieces the free passage, not only of the gases, but also the liquid.
A complete filling of the cell is thus obtained, through a bubble-free liquid.
Of course, the realization of this cell is particularly economic and simple .